A Georgia widow facing more than a dozen charges relating to the investigation into her husband's 2010 murder is believed by prosecutors to have lied in court about an affair with the man convicted of shooting her husband.

Andrea Sneiderman, 37, is on trial for charges including lying under oath, perjury and hindering the investigation into the murder of her husband, Rusty Sneiderman.

Hemy Neuman was convicted in March 2012 of murdering Rusty Sneiderman, 36, in the parking lot of Sneiderman's son's day care center in Dunwoody, Ga., and sentenced to life in prison.

Prosecutors allege that Andrea Sneiderman and Neuman were having an affair.

"The evidence will show a forbidden romance that ends in murder, silence despite her suspicion, and lies to conceal the truth from her family, from her friends, from the police and from a jury," Hill said during opening statements Monday.

Prosecutors allege Sneiderman kept the information about her affair from investigators, even while she was staring into the face of a police sketch of the shooter.

Rusty Sneiderman had just dropped off their young son when he was gunned down outside a suburban Atlanta preschool. Six weeks later, police arrested Neuman, who was Andrea Sneiderman's supervisor at her job at General Electric.

Prosecutors started to suspect during Neuman's trial that Andrea Sneiderman was having an affair with her boss, and her defiant attitude on the witness stand didn't mitigate their suspicions. While testifying under oath, Sneiderman denied having the affair, saying she put up with Neuman's unwanted advances to keep her job.

"None of those feelings were ever returned, and I made myself completely clear," Sneiderman said in court in 2012.

Neuman was convicted in the killing in March 2012, but he was found to be mentally ill. Four months after his trial, Sneiderman was indicted for murder and lesser charges, and arrested.

The district attorney eventually asked the judge to dismiss the three most serious charges, including murder, after the DA's office received evidence from the defense that prompted him to re-interview witnesses, leading to his decision. The judge allowed the dismissal.

Sneiderman has pleaded not guilty to all charges against her. She faces up to 10 years in prison.

But in court Monday, jurors heard from a number of witnesses called by the state, including a waitress who said she saw Neuman and Sneiderman passionately kissing on a business trip in South Carolina in 2010.

"This was a kiss like a loving kiss, like a passionate kiss," Christine Olivera told the court.

Sneiderman's lawyers insist she did nothing wrong, and said that it was she who gave police Neuman's name within 36 hours of the shooting.

"It was Andrea Sneiderman who first inserted the name of Hemy Neuman into the investigation," defense attorney Tom Clegg told the court, adding that Neuman "was a pest … a nuisance."

B.J. Bernstein, a top Atlanta attorney with no connection to the prosecution or Sneiderman, said it is unclear what exactly happened to Sneiderman's husband.

"Affairs happen every day, people deny affairs, that's what the divorce courts are filled with," he told ABC News. "The component here was that done in such a way that the police and prosecutors couldn't get the truth as to what happened to Rusty Sneiderman."